This invention relates generally to inflatable passive restraint systems for use in vehicles for restraining the movement of a seated occupant during a collision and, more particularly, to an improvement in the structure for housing and positioning a gas generator and inflatable bag in the vehicle.
Safety restraint systems which self-actuate from an undeployed to a deployed state without the need for intervention by the operator, i.e., "passive restraint systems", and particularly those restraint systems incorporating inflatable bags or cushions, as well as the use of such systems in motor vehicles have been the subjects of much discussion as the desirability of the use of such passive restraint systems has gained general acceptance in the United States.
It is well known to protect a vehicle occupant using a cushion or bag that is inflated with gas, e.g., an "inflatable bag" or, commonly referred to as an "air bag", when the vehicle encounters sudden deceleration, such as in a collision. During deployment, the rapidly evolving gas with which the bag is typically filled is an inert gas, e.g., nitrogen. In such systems, the inflatable bag is normally housed in an uninflated and folded condition to minimize space requirements. Upon actuation of the restraint system, gas is discharged from an inflator to rapidly inflate the bag. The bag can then serve to restrain the movement of the vehicle occupant as the collision proceeds.
Vehicular inflatable restraint systems generally include multiple crash sensors generally positioned about or mounted to the frame and/or body of the subject vehicle and serve to sense sudden decelerations by the vehicle. In turn, the sensor sends a signal to an inflatable bag module/assembly strategically positioned within the riding compartment of the vehicle to actuate deployment of the air bag. In general, an inflatable bag provided for the protection of a vehicle driver, i.e., a driver side air bag, is mounted in a storage compartment located in the steering column of the vehicle. Whereas, an inflatable bag for the protection of a front seat passenger, i.e., a passenger side air bag, is typically mounted in the instrument panel/dash board of the vehicle.
Typical inflatable passive restraint systems make use of an air bag module which generally includes an outer reaction housing or canister, commonly referred to as a "reaction can" or, more briefly, as a "can". The reaction canister generally serves to support or contain other components of the air bag module system, including what is referred to as a "air bag inflator" or, more briefly, as an "inflator", or, alternatively, as a "generator". The inflator, upon actuation, acts to provide the gas to inflate the bag.
In addition to providing protection for the gas generator and the inflatable bag until the time of deployment of the latter, the housing structure also acts to absorb the loads generated by the deployment of the bag. Typically, these loads are large and unless sufficiently absorbed can cause damage to the vehicle including, in the case of a passenger side assembly, damage to the dash panel. Thus, it has been a practice in the prior art to use heavyweight structures, particularly steel structures, for housing and positioning an inflator, particularly an inflator for a passenger side assembly, in order to prevent or minimize such damage.
Emphasis on weight reduction in automobiles, however, has created a need, and a demand, for a lighter weight passenger side inflatable passive restraint system. A most significant reduction in the weight of the system can be achieved through the utilization of aluminum rather than a heavy steel material, as used in previous structures, in the reaction canister structure used to house and position the inflator and inflatable bag. The use of aluminum in such inflatable passive restraint systems is disclosed, for example, in commonly assigned U.S. Pat. Nos. 4,547,342, issued Oct. 15, 1985 to Adams et al., and 4,561,675, issued Dec. 31, 1985 to Adams et al.
More particularly, commonly assigned U.S. Pat. No. 4,941,678, Lauritzen et al., issued Jul. 17, 1990, discloses a lightweight housing canister assembly having a design avoiding such bell mouthing. The assembly includes a body part, such as made of by continuous aluminum extrusion. The assembly further includes a tether strap, at the mouth inside the bag. The tether strap serves to: 1) restrict the loading of the reaction canister that is positioned transversely thereto and 2) retain the spreading forces at the mouth of the canister upon bag deployment. This allows the use of a lighter section at the mouth of the canister and eliminates the need for reinforcing flanges along the sides of the canister, which flanges would undesirably increase the weight of the assembly. The structural arrangement of the Lauritzen et al. patent, however, complicates the manufacturing and assembling operations, and moreover, does not allow installation of the inflator as a last operation in the assembly of the module.
Thus, there is a need and a demand for an improved structural arrangement which permits the more widespread usage of lighter weight assemblies.
In addition, while most inflatable passive restraint systems for automobiles contain common basic components including an air bag, an inflator, and a reaction canister, the systems are installed in vehicles of a variety of different sizes and shapes. Further, there are a variety of different types of inflators such as pyrotechnic, stored gas or hybrid inflators, for example and which inflators can take a variety of shapes and/or sizes as the inflators are specifically designed for particular applications.
As a result, there is a need for a reaction canister structure having applicability in a wide variety of applications and in which an inflator selected from a wide variety of inflator devices can be utilized. That is, there is a need for a reaction canister structure that is capable of a more widespread or universal utilization and applicability.
Further, there is a need and a demand for an improved structural arrangement which is conducive to the economical and effective incorporation of various desired features, such as various mounting or attachment preparations, for example, in particular vehicular inflatable restraint system design applications.
Still further, there is a need for such a structural arrangement which permits the installation of an inflator as a last operation in the assembly of a respective air bag module.